title: Respiratory CO₂ response in acute cervical spinal cord injury (CO₂ response in spinal cord injury).
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  The objective of this study was to compare the CO₂ response of acute tetraplegic cervical spinal cord injury (SCI) patients undergoing mechanical ventilation with a control group of critically ill patients ready for weaning of mechanical ventilation and successfully extubated.
  
  
  METHODS
  This study was conducted at the intensive care unit of a University Hospital in Mallorca, Spain.
  
  
  METHODS
  CO₂ response was studied in 12 acute tetraplegic cervical SCI patients at the C4-C7 level and 22 control patients. The control group patients were consecutively selected from a database of patients with mechanical ventilation and who were successfully extubated after a CO₂ response test. To increase the CO₂ , we used the method of re-inhalation of expired air, and we evaluated the hypercapnic ventilatory response, the change in minute ventilation induced by the increase of partial pressure of arterial carbon dioxide (PaCO₂ ), which measures the whole respiratory system (metabolic control, neuromuscular or ventilatory apparatus), and the hypercapnic drive response, the change in the airway occlusion pressure at 100 ms induced by the increase in PaCO2, which measures the chemosensitivity of the respiratory center.
  
  
  RESULTS
  Cervical SCI patients were younger than the control group patients (26±7 and 62±12 years, respectively; P<0.001). Mean values of the hypercapnic ventilatory response in cervical SCI and control groups were 0.52±0.31 and 0.64±0.33 l min(-1) per mm Hg (P=0.40), respectively, and the hypercapnic drive response was 0.24±0.16 and 0.48±0.23 cm H₂O per mm Hg (P=0.001), respectively.
  
  
  CONCLUSIONS
  Acute tetraplegic cervical SCI patients had reduced hypercapnic drive response that may contribute to the difficult weaning, without reduction in hypercapnic ventilatory response.
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Espases, Palma de Mallorca, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Raurich
authors.affiliation: Hospital Universitari Son Llàtzer, Palma de Mallorca, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Rialp
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Espases, Palma de Mallorca, Spain.
authors.forename: J A
authors.initials: JA
authors.lastname: Llompart-Pou
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Espases, Palma de Mallorca, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Ayestarán
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Espases, Palma de Mallorca, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Pérez-Bárcena
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Espases, Palma de Mallorca, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Ibáñez
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000097:blood*; D002574:Cervical Vertebrae; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D008297:Male; D012123:Pulmonary Ventilation / Q000502:physiology*; D011782:Quadriplegia / Q000209:etiology / Q000503:physiopathology; D012121:Respiration, Artificial; D012189:Retrospective Studies; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology* / Q000628:therapy*
chemical_list: D002245:Carbon Dioxide